1. Field of the Invention
The present invention relates to a semiconductor device, and particularly to a TAB (Tape Automated Bonding) type semiconductor device.
2. Description of the Related Art
FIGS. 1 and 2 are diagrams showing the conventional bonding structure of a TAB tape and a semiconductor chip.
In the conventional bonding structure, shown in FIGS. 1 and 2, inner leads 4 formed on a TAB tape 7 are each bonded to an electrode pad portion of a semiconductor chip 3, and the semiconductor chip 3 is supported in a device hole 2 by only the inner leads 4. In the conventional bonding structure of the TAB tape 7 and the semiconductor chip 3 as described above, stresses are applied to the inner leads 4 due to the dead weight of the semiconductor 3 itself and vibrations occurring in the fabricating process, resulting in reduction in mechanical strength and finally in cutting of the inner leads 4. The pads of the semiconductor chip 3 tend to be arranged with a smaller interval, and this tendency of the pad arrangement also promotes reducing of the width of the inner lead 4 of the TAB tape 7. Therefore, it is expected that it will be difficult to support the semiconductor chip 3 by only the inner lead 4.
Furthermore, there has been proposed a semiconductor device in which support leads are bonded to empty electrode pads which are not required to be electrically connected, thereby enhancing the mechanical strength for supporting the semiconductor chip 3 (see Japanese Patent Application Laid-open No. Hei-3-72643, for example). In this system, the number of support leads is reduced when the number of empty pads is small, and thus this system is not so effective for enhancing mechanical support strength.
As described above, in the conventional bonding structure, the mechanical strength is increasingly reduced as stresses are applied to the inner leads, and finally the inner leads are cut or broken.
Furthermore, as described above, the interval of the pad arrangement on the semiconductor chip tends to be smaller, and thus the inner leads also tend to be narrower. However, the conventional bonding structure has not been able to follow this width-narrowing tendency.